Gas-compressing pump



` (No Model.) r

W. W. DOOLITTLE.

GAS GOMPRESSING PUMP.

' Patented Oct. 10, 1882.(

v vzzu jnesgey; A I veya- 03 1 UNrra States AraNr rripa@ VVILLIAM W. DOOLITTLE, OF CHICAGO, ILLINOIS.

GAS-COMPRESSING PUMP.

SPECIFICATION forming part of Letters Patent No. 265585, dated October 10, 1882.

Applcatiou filed May 26, ISS-2. (No model.)

To all whom tt may conccrn Be it known that I, WM. W. DOOLITTLE, residing at Chicago, in the county ot' Cook and State of Illinois, and a citizen of the United States, have invented a new and useful Improvement in Gas Compressing Pumps, ot' which the following is a full description, reference being had to theaccompanying drawings, in which Figure l is a central longitudinal or vertical section. Fig. 2 is a modification.

In the operation of single-acting gas-compressing pumps a portion of the gas escapes or leaks around the piston-head, and passes from that end ot' the cylinder in which the compression takes place into the opposite end; and, further, in such punps a partia-l Vacuum is created in the non-compressing end of the cylinder.

One' object of my invention is to provide improved means for saving the gas which leaks past the piston and at the same time prodnoe but little or no pressure on 'the stufting-box, and also prevent the formation of a partial vacuum in the cylinder. \Nhen the movement of the piston is in the proper direction for compressing the gas, which I accomplish by means ot' two single-acting cylinders,'each having at one end inlet and outlet valves and communicating with each other at their opposite ends, and by providing` some suitable relief through which communication is had with the said cylinder upon opposite sides of its piston independent of the inlet-pipe. When the pnmp stops the piston-head is liabie to stop at or near the center of the cylinder and under a great pressure, when moving toward the discharge end ot' the cylinder, and on account of such pressure it is often very difficult to start the pump again.

Another object of my invention is to obviate the last-mentioned difiieulty, which I accomplish by providing a small relief-valve, as herenafter described.

In the drawings, A A' represent two punpcylinders, each provided with heads B and B' in the usual manner.

C G' are the pistons, and D D' are the piston-rods, which pass through suitable stufin gboxes.

E is the inlet for gas into thecylinder A, the gas passing through the inlet-valve F.

G is the outlet-valve through which the compressed gas goes to the outlet-passage H.

E' F' G' H' are corresponding passages and valves for the cylinder A The opposite ends of the two cylinders are connected together by means' of a passage, I.

a is a passage leading from one end ot' the cylinder A to the opposite end, the inlet to the upper end ot' the cylinder from the passage a being controlled by a small valve, I).

The Construction and operation of the valves F, Gr, F', G', and b will be understood from the drawings without further description.

c is a valve controlling a small openinginto the upper end of the cylinder A', which opening d conimunicates also with theinlet-passage, E'. This valve may be operaied by a handwheel, e. The other cylinder, A, is also provided with a valve similar to c, which Controls a passage similar to the passage d.

f is a hand-wheel for Operating the lastmentioned valve, which is located partly behind F.

The operation is as follows: The gas which escapes around the piston G will pass through the passage a and valve I) into the upper end of the cylinder A, when the pressure is sufficient to overcome the tension of the spring which holds the valve b to its seat, and'if a light spring be used for this purpose the pressure of the gas in thelower endof this cylinder will be small. The gas which escapes around the piston G' will pass into the cylinder A through the passage I,andthence through the passage a into the upper end of the cylinder A through the valve Z). By this arrangement there never will be but little pressure upon the stufling-boxes.

In consequence of the communication between the lower' ends of the two cyliuders throughthe passage I, a partial vacuum can never be formed behind either'piston, air or gas passing from one to the other behind the pistons, according to the direction, in which they move.

By means of the valve c and a corresponding valve for the other cylinder, the cylinders can be relieved from any compressed gas theren when the punps stop, which is a desirable feature to facilitate the starting of the pumps. 4

Instead of the passage a for opening com- IOO munication between the two ends of one ot' the c vlinders, the same result could he accomplished by means of a valve located in one of the pistons, as shown in Fig. 2.

It' it should he found advisable to use cylinders of different sizes, the pipe I could be made to communicate with a chamberof suitable size located between the two cylinders for the purpose of equalizing the pressure.

As shown and described, the outer end of the passage d communicates with the inletpassage E', and a passage in the other cylinder corresponding to d is supposed to communicate with the iulet-passage E. This passage d and the corresponding passage in the other cylinder might be connected by neans ot' a suitable pipe directly with the chamber from Whichgas is supplied to the cylinders; hnt there would beno advantage from this construction.

The two cylinders may he located side by side, or at a distance from each other, and in operation the piston-rods which are connected with cranhs moving in opposite directions or with other devices that will cause one pisten to have a forward movement in its cylinder while the piston of the other cylinder has a return movement at the same time in the usual anner of single-acting pumps--thatis to say, when the piston in the cylinder A has a forward movement to discharge the air or gas through the pipe H the piston in the c vlinder A' will have a return movement to fill such cylinder through the pipe E'. The passage I permits a free flow of air or gas from one cylinder to the other in the descent ot' the piston, so that no compression can he had in either eylinder hack of the piston. The passage a furnishes a relief by which any air or gas back ot' the piston can escape and pass to the cylinder forward of the pisto, and this same result is produced by the vzlve located in the piston, such Valve opening in the (lescent ot' the piston and closing with the ascent, so that by either means a relief is provided for the gas or air hack ot' the piston by which such gas or air escapes, producing no resistance to the piston, and as both cylinders are connected it will be seen that a relief in one eylinder will act for both. A

It will be seen that by this arrangement of cylinders communicating with each other and providing a relief back of the pistons but little, it' any, pressure is on the stutfing-boxes.

What I claim as new, and desire to secure by Letters Patent, is as follows:

1. Two single-acting pump-cylinders, each provided at one end with an iulet and an outlet passage controlled hy valves and communicating with each other at their opposite ends, and one of said cylinders having a relief controlled by a valve, through which com nunica-.

tion is had with the cylinder upon opposite sides of its piston, substantially as and for the purposes specified.

2. Two single-acting pump-cylinders, each provided at one end with an inlet and an outlet passage controlled by valves and communicating with each other at their opposite ends hy means ot' a pipe, I, or other suitable passage, and one of the cylinders having a passage,a communicating with the opposite ends of said cylinder and controlled hyavalve,snhstantially as and for the purposes specified.

ln a pun p t'or com pressing gas, a secondary relief-valve, c, located in that end ot' the cylinder in which compression takesplace, and controlling a passage, one end of which communicates with the cylinder, while the other end communicates with the pipe or chamber 'from which gas is supplied to the cylinder for the purpose of 'elieving the pressure in the cylinder to facilitate the starting of the pump, substantially as specified.

VVILLIAM XV. DOOLITTLE. lVitnesses:

E. A. WEST, 0. W. BOND. 

